Compound barb medical device and method

ABSTRACT

Barbed medical devices include a crown interconnecting a pair of legs and at least one barb extending from each of the legs. The at least one barb may define an inner surface with a first portion disposed at a first orientation relative to a longitudinal axis of the leg, a second portion disposed at a second orientation relative to the longitudinal axis, and optionally, a third portion disposed at a third orientation relative to the longitudinal axis of the leg.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.12/726,815, filed Mar. 18, 2010, which is a continuation-in-part of U.S.patent application Ser. No. 12/361,962, filed Jan. 29, 2009, now U.S.Pat. No. 8,273,105, which claims the benefit of and priority to U.S.Provisional Application No. 61/029,964, filed Feb. 20, 2008, the entiredisclosures of each of which are incorporated by reference herein.

TECHNICAL FIELD

The present disclosure relates generally to forming barbs on medicaldevices. In particular, the present disclosure relates to compound barbmedical devices including shape memory polymeric materials, and methodsof forming and using such medical devices.

BACKGROUND OF RELATED ART

Barbed sutures are known for use in medical procedures. Theconfiguration of barbs on a barbed suture may be designed to optimizetissue holding for a particular indication. In some circumstances, arandom configuration of barbs on the exterior surface of the suture maybe preferred to achieve optimal wound closure. However, in othercircumstances, where the wound or tissue repair needed is relativelysmall, a reduced number of barbs may be desired. In still othercircumstances, a bidirectional barbed suture may be desirable to permitpassing of the suture through tissue in one direction over a portion ofthe suture and permit passing of the suture through tissue in a seconddirection over another portion of the suture.

While various methods of forming barbs on sutures have been proposed,such methods may be difficult or costly to implement. Thus, thereremains room for improvement with respect to barbed sutures and methodsfor making them.

Moreover, surgical fasteners or staples may also be used in surgicalprocedures to fasten body tissue. Typically, a staple is a U-shapedmember including a back span and two legs which are bent by a deliverydevice to hook body tissue together. An anvil of a stapler generallycrimps the staple, and thus, conventional staplers typically comprisecomplex structures which must not only eject the staples but to do so ina manner such that the staple deforms properly and timely.

Two part fasteners have also been used in which a staple includes barbedprongs which engage a separate retainer piece. In use, the staple ispressed into the body tissue so that the barbs penetrate the tissue andemerge from the other side where they are then locked into the retainerpiece.

Thus, there remains room for improvement with respect to barbed staplesand methods for making them.

SUMMARY

The present disclosure is directed to a compound barb medical deviceincluding a crown interconnecting a pair of legs; and at least one barbextending from each of the legs, the at least one barb defining an innersurface, the inner surface including a first portion disposed at a firstorientation relative to a longitudinal axis of the leg and a secondportion disposed at a second orientation relative to the longitudinalaxis. The inner surface of the compound barb medical device may includecomprise a third portion disposed at a third orientation relative to thelongitudinal axis.

More specifically, the first angle of the compound barb medical devicehave include the first angle is about 0 degrees to about 90 degrees, inembodiments, from about 30 degrees to about 40 degrees, and in furtherembodiments, from about 31 degrees to about 38 degrees.

The second angle of the compound barb medical device may be of fromabout 0 degrees to about 90 degrees, in embodiments, from about 1 degreeto about 10 degrees, and in further embodiments, from about 2 degrees toabout 8 degrees.

The third angle of the compound barb medical device may be from about 0degrees to about 90 degrees.

In certain embodiments, at least one of the first, second, and thirdportions is substantially linear. The compound barb medical device mayinclude at least one of the first, second, and third portions aredisposed at first, second, and third angles relative to respectivelongitudinal axes of each leg. Alternatively, at least one of the first,second, and third portions is substantially non-linear. The non-linearportion may be cut at a radius relative to the longitudinal axis of theleg.

The compound barb medical device may be formed from an absorbable ornon-absorbable material. The non absorbable material may be selectedfrom titanium, stainless steel, polyolefins, polyamides, polyamines,polyimines, polyesters, fluoropolymers, polyether-esters,polytetramethylene ether glycol, 1,4-butanediol, polyurethanes,copolymers, and combinations thereof. The absorbable matieral maycomprise a dissolvable metal, polyesters, polyorthoesters, polymerdrugs, polydroxybutyrates, dioxanones, lactones, proteins, cat gut,collagens, carbonates, alkylene carbonates, caprolactone, glycolic acid,lactic acid, glycolide, lactide, homopolymers, copolymers, andcombinations thereof. Further, the compound barb medical device maycomprise a bioactive agent.

A method of forming a compound barb on a staple is also disclosed,including providing a staple having a pair of legs, each leg defining alongitudinal axis; and applying vibrational energy to a cutting elementto form a compound barb on at least a portion of each leg including:forming a first cut in the leg, the first cut having a first ratio ofcut depth to diameter of the leg; and forming a second cut in the leg,the second cut having a second ratio of cut depth to diameter of theleg.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the present disclosure will be described hereinbelow with reference to the figures wherein:

FIG. 1 is a plan view of a barbed medical device having compound barbsformed in accordance with the present disclosure;

FIG. 2 is a plan view of a two way barbed medical device having compoundbarbs formed in accordance with the present disclosure;

FIG. 3 is a plan view of an alternative embodiment of a barbed medicaldevice having both single angle barbs and compound barbs formed inaccordance with the present disclosure;

FIG. 4A is a plan view of a segment of a barbed medical having compoundbarbs formed in accordance with the present disclosure;

FIG. 4B is a plan view of an alternative embodiment of a segment of abarbed medical having compound barbs formed in accordance with thepresent disclosure;

FIG. 5 is a plan view of a segment of a bi-directional barbed medicaldevice having compound barbs formed in accordance with the presentdisclosure;

FIG. 6 is a plan view of an alternative embodiment of a barbed medicaldevice having compound barbs formed in accordance with the presentdisclosure;

FIG. 7 is a plan view of an alternative embodiment of a barbed medicaldevice having compound barbs formed in accordance with the presentdisclosure;

FIG. 8 is a plan view of a segment of a barbed suture having compoundbarbs and a loop formed at one end in accordance with the presentdisclosure;

FIG. 9 is a schematic view of an embodiment of an apparatus and methodof forming barbs on a medical device in accordance with the presentdisclosure;

FIG. 10 is a plan view of an alternate embodiment of a segment of abarbed medical device having compound barbs formed in accordance withthe present disclosure;

FIG. 11 is a plan view of another embodiment of a segment of a barbedmedical device having compound barbs formed in accordance with thepresent disclosure; and

FIG. 12 is a plan view of a barbed staple having compound barbs formedin accordance with the present disclosure.

DETAILED DESCRIPTION

Referring in detail to the drawings in which like reference numerals areapplied to like elements in the various views, FIG. 1 illustrates amedical device 100 having an elongated body 14 and at least one compoundbarb 12 extending from the elongated body 14. Compound barb 12 definesan inner surface which includes a first portion 12 a disposed at a firstorientation relative to the longitudinal axis of elongated body 14, asecond portion 12 b disposed at a second orientation relative to thelongitudinal axis, and a third portion 12 c disposed at a thirdorientation relative to the longitudinal axis.

Compound barbs 12 include at least one substantially linear portion. Asillustrated in FIG. 1, first, second and third portions 12 a-c aresubstantially linear. It is envisioned that at least one of the portionsmay be substantially non-linear, such as for example, arcuate asdescribed hereinbelow.

As shown in the exemplary embodiment of FIG. 1, compound barbs 12 may beformed projecting from the medical device 100 towards at least one endof medical device 100. In other alternative embodiments, multiplecompound barbs may be formed such that some of the barbs project towardone end of the medical device and the remaining barbs project toward theother end of the medical device so as to form a bi-directional medicaldevice 200 as generally illustrated in FIG. 2. Alternatively, aplurality of axially spaced barbs may be formed in the same or randomconfiguration and at different angles in relation to each other.Optionally, the medical device may include a plurality of barbs spacedat the same or different lengths according to the type of tissue beingmanipulated and/or procedure performed (not shown). In some embodiments,the compound barb medical device incorporates a loop at the proximal endthereof configured to enhance retention of the medical device in bodytissue at a desired position.

In an alternative embodiment, medical device 300 may be formed toinclude a combination of compound barbs 12 and single angle barbs 13 asshown in FIG. 3. In such an embodiment, the compound barbs 12 and singleangle barbs 13 may be formed along the length of the medical device 300in specified or random patterns. Additionally, the medical device 300may be formed such that compound barbs 12 are all oriented in the samedirection toward one end of medical device 300 and the single anglebarbs 13 are all oriented in the same direction toward the other end ofmedical device 300.

Referring to FIG. 4A, compound barbs 12 having first, second and thirdportions 12 a-c are generally formed by cutting into the surface ofelongated body 14. In embodiments, each of the first, second, and thirdportions 12 a-c may be cut at first, second and third angles α, β, and γrelative to longitudinal axes a, b, and c respectively of elongated body14. Longitudinal axes a, b, and c are parallel to a central longitudinalaxis D′, and the second angle β is less than the first angle α, and thethird angle γ is less than the second angle β. Compound barb 12 mayinclude a first portion 12 a which is formed by cutting into elongatedbody 14 at a first angle α of from about 0 degrees to about 90 degreesrelative to longitudinal axis “a”, in embodiments, the first angle αranges from about 30 degrees to about 50 degrees relative tolongitudinal axis “a”. A second portion 12 b may be formed by cuttinginto elongated body 14 at a second angle β of from about 0 degrees toabout 90 degrees relative to the longitudinal axis “b”, in embodiments,the second angle β ranges from about 2 degrees to about 25 degreesrelative to the longitudinal axis “b”. A third portion 12 c may beformed by cutting into elongated body 14 at a third angle γ of fromabout 0 degrees to about 90 degrees relative to longitudinal axis “c”,in embodiments, the third angle γ ranges from about 2 degrees to about50 degrees relative to longitudinal axis “c”.

Referring now to FIG. 4B, each of the first, second and third portions12 a′-c′ may be cut at first, second and third angles α′, β′ and γ′relative to the longitudinal axes “a”, “b′”, and “c′”, respectively, ofelongated body 140, such that angle α′ is greater than angle β′ andangle γ′ is less than angle β′. Compound barb 120 may include a firstportion 120 a which is formed by cutting into elongated body 140 at afirst angle α′ of from about 0 degrees to about 90 degrees relative tolongitudinal axis “a′”, in embodiments, the first angle α′ ranges fromabout 30 degrees to about 50 degrees relative to longitudinal axis “a′”.A second portion 120 b may be formed by cutting into elongated body 140at a second angle β′ of from about 0 degrees to about 90 degreesrelative to longitudinal axis “b”, in embodiments, the second angle β′ranges from about 30 degrees to about 60 degrees relative tolongitudinal axis “b”. A third portion 12 c may be formed by cuttinginto elongated body 140 at a third angle γ′ of from about 0 degrees toabout 90 degrees relative to longitudinal axis “c′”, in embodiments, thethird angle γ′ ranges from about 25 degrees to about 50 degrees relativeto longitudinal axis “c′”.

In other embodiments, a compound barb medical device includes anelongated body having first and second portions, the first and secondportions of the elongated body are at first and second angles respectiveto a longitudinal axis of the elongated body to form at least onecompound barb (not shown). Optionally, the elongated body of thecompound barb medical device may include a third portion at a thirdangle respective to a longitudinal axis of the elongated body.

Such an embodiment of a compound barb suture is shown in FIG. 10. Thecompound barb 620 includes two portions 620 a, 620 b which are disposedat two angles, α″ and β″ relative to a longitudinal axis of the medicaldevice. More specifically, the compound barb 620 includes a firstportion 620 a formed from the elongated body 610 at a first angle α″,which is from about 0 degrees to about 90 degrees, in embodiments, fromabout 30 degrees to about 40 degrees, and in further embodiments, fromabout 31 degrees to about 38 degrees, relative to a longitudinal axisA-A of the elongated body 610. The second portion 620 b is formed fromthe elongated body 610 at a second angle β″ which is from about 0degrees to about 90 degrees, in embodiments, from about 1 degrees toabout 10 degrees and in further embodiments, from about 2 degree toabout 8 degrees relative to the longitudinal axis A-A of the elongatedbody 610.

Another embodiment of a compound barb device is shown in FIG. 11. Anelongated body 700 is shown including a compound barb 720 having a firstlinear portion 720 a, shown at an angle γ″, relative to a longitudinalaxis B-B of the elongated body 700. Extending from the first portion 720a is an arcuate second portion 720 b at a radius r₇. The elongated body700 also includes a compound barb wherein a first portion 740 a isarcuate and a second portion 740 b is linear.

FIG. 5 illustrates compound barb 12 having three portions 12 a-c, asillustrated in FIG. 4A, and compound barb 120 having three portions 120a′-c′ as illustrated in FIG. 4B, formed such that some of the barbsproject toward one end of medical device 500 and the remaining barbsproject toward the other end of medical device 500 so as to form abi-directional medical device 500. In alternative embodiments, compoundbarbs are formed such that the barbs projecting toward one end, forexample, towards the proximal end, have the same orientation and anglesas the barbs projecting towards the other end, for example, towards thedistal end.

In some embodiments, the compound barb may include at least one portionwhich is substantially non-linear. In embodiments, the barbs may includeat least one point of inflection which may define a concave portion, aconvex portion, an arcuate portion and combinations thereof. Forexample, at least one of the portions may be cut at a radius relative tothe longitudinal axis of elongated body 240. As shown in FIG. 6,compound barb 220 may include an arcuate second portion 220 b. Thearcuate portion 220 b may be cut at a radius r₁ relative to thelongitudinal axis of elongated body 240.

In alternative embodiments, an optional fourth portion may be cut at afourth radius. In some embodiments, each of the first, second, third andoptional fourth portions 320 a-d may be cut at first, second, third andfourth radii relative to the longitudinal axis of elongated body 340. Asillustrated in FIG. 7, compound barb 320 may include an arcuate firstportion 320 a which extends away from elongated body 340 at a firstradius r₂, an arcuate second portion 320 b which extends from firstportion 320 a at a second radius r₃, an arcuate third portion 320 cwhich extends from second portion 320 b at a third radius r₄, and anarcuate fourth portion 320 d which extends from third portion 320 c at afourth radius r₅.

In other embodiments, a compound barb medical device may include anelongated body having a barb and first, second, and third portions beingcut at first, second, and third angles respective to a longitudinal axisof the elongated body to form the barb.

The medical device in accordance with the present disclosure may beformed of the type selected from the group consisting of monofilamentsutures, braided sutures, multi-filament sutures, surgical fibers,staples, anchors, slit sheets, ribbons, tape, mesh, stent, scaffolds,pledgets, vascular graft and ribbons. In an exemplary embodiment, themedical device is a suture. In another exemplary embodiment, the medicaldevice is a staple.

The exemplary medical devices illustrated throughout the figures areshown to be elliptical in cross-sectional geometry. However, thecross-sectional geometry of the medical device may be of any suitableshape, for example, round, square, star shaped, octagonal, rectangular,polygonal and flat.

In some embodiments, a loop is formed at the proximal end of thecompound barb medical device which is configured to enhance retention ofthe medical device in body tissue at a desired position. As illustratedin FIG. 8, loop 410 is formed at the proximal end of the compound barbmedical device 400. Loop 410 may be fixed at a predetermined locationalong the length of the elongated body 440 of the compound barb medicaldevice 400. Loop 410 may be configured and dimensioned to be adjustablealong the length of elongated body 440 (not shown).

In general, a method for forming a compound barb on a medical deviceincludes the steps of providing a medical device, or a portion thereof,having a longitudinal axis and forming a compound barb along the medicaldevice wherein the compound barb defines an inner surface which includesat least a first portion disposed at a first orientation relative to thelongitudinal axis, a second portion disposed at a second orientationrelative to the longitudinal axis, and optionally a third portiondisposed at a third orientation relative to the longitudinal axis. Inembodiments, at least one of the first, second, and third portions issubstantially linear. In alternative embodiments, at least one of thefirst, second, and third portions is substantially non-linear orarcuate.

In embodiments, a method of forming a compound barb on a medical deviceincludes forming a first cut in the medical device, the first cut havinga first ratio of cut depth to diameter of the elongated body of themedical device; forming a second cut in the medical device, the secondcut having a second ratio of cut depth to diameter of the elongated bodyof the medical device; and forming a third cut in the medical device,the third cut having a third ratio of cut depth to diameter of theelongated body of the medical device.

FIG. 9 illustrates an embodiment of an apparatus and method of formingcompound barbs in accordance with the present disclosure. The method isdescribed, for example in U.S. patent application Ser. No. 12/178,361filed Jul. 23, 2008 and titled “Method of Forming Barbs on a Suture”,the entire disclosure of which is incorporated herein by reference. Inthe illustrative embodiment, ultrasonic energy is generated by anapparatus 60 that includes a converter 62 which transmits ultrasonicenergy to a horn 66 that is operatively coupled to converter 62.Converter 62 converts electrical energy to mechanical energy whichcauses displacement of the tool at an ultrasonic frequency powered by anultrasonic generator or booster 68. Booster 68 may be manipulated toeither increase or decrease the ultrasonic frequency which may betransmitted to the tool. The ultrasonic frequency may range from about 1kHz to about 100 kHz. In other embodiments, the ultrasonic frequency mayrange from about 10 kHz to about 90 kHz. In still further embodiments,the ultrasonic frequency may range from about 15 kHz to about 50 kHz.The ultrasonic signal amplitude may range from about 1μ to about 125μ.In other embodiments, the signal amplitude may range from about 15μ toabout 60μ.

The ratio of the cut depth and the angle of the barbs relative to theelongated body of the medical device are variable based on the signalamplitude of ultrasonic energy applied to the cutting element. Forexample, as the ultrasonic amplitude is increased, the ratio of the cutdepth to the diameter and the angle of the barbs are decreased. As theultrasonic amplitude is decreased, the ratio of the cut depth to thediameter is increased, thereby increasing the angle of the barbs.

Referring back to FIG. 4A, in some embodiments, the compound barbs 12 asformed have a first angle α of approximately 0 degrees to about 90degrees, in embodiments, from 30 degrees to 50 degrees between compoundbarb 12 and elongated body 14 and a first ratio of cut depth which isapproximately 1% to about 40%, and in certain embodiments, about 10% toabout 30% of the diameter of the body. Compound barb 12 as formed by themethod of the present disclosure may have a second angle β ofapproximately 0 degrees to about 90 degrees, in embodiments, from 2degrees to 25 degrees relative to the longitudinal axis with a secondratio of cut depth of approximately 5% to about 50%, and in certainembodiments, about 15% to about 45% of the diameter of elongated body14. Compound barb 12 as formed by the method of the present disclosuremay have a third angle γ of approximately 0 degrees to about 90 degrees,in embodiments, from about 25 degrees to about 50 degrees relative tothe longitudinal axis with a third ratio of cut depth of approximately15% to about 50%, and in some embodiments, from about 30% to about 50%the diameter of elongated body 14. In one embodiment, a plurality ofbarbs are formed at successive intervals along the longitudinal axis ofthe medical device.

With continued reference to FIG. 9, the apparatus 60 optionally includesa gripper such as anvil 70 for supporting a medical device. The gripper70 supports the medical device at a fixed position. The horn 66 isconfigured and dimensioned to accept a cutting element such as a knifeblade or a rotary blade (not shown) for forming the barbs on the medicaldevice. The motorized slide 74 moves in an X, Y, and Z plane to allowthe medical device to pass in front of the converter to form barbsthereon. Apparatus 60 also includes rotational motor 76 which rotatesthe medical device in a circular direction. Advance slide 78 moves themedical device after every cut a specified increment for the appropriatebarb spacing. Apparatus 60 optionally includes camera 72 for recordingthe method of forming barbs and a light source 74 for optimizing theview of camera 72.

In embodiments, the medical device is moved to be in contact with thecutting element, or in other embodiments, the medical device is movedagainst the cutting element, at a specified first angle relative to thelongitudinal axis of the elongated body of the medical device to form afirst ratio of cut depth to diameter of approximately 1% to about 40%,in other embodiments a first ratio of cut depth to diameter ofapproximately 10% to about 30%. While the cutting element is still incontact with the medical device, a second angle is cut having a ratio ofcut depth to diameter of approximately 5% to about 50%, in otherembodiments a ratio of cut depth to diameter of approximately 15% toabout 45%. Optionally, in other embodiments, while the cutting elementis still in contact with the medical device, a third angle is cut havinga ratio of cut depth to diameter of approximately 15% to about 50%, inother embodiments a ratio of cut depth to diameter of approximately 30%to about 50%.

The amount of time the blade is in contact with the medical deviceranges, in embodiments, from about 1 millisecond to about 5 seconds. Inother embodiments, the amount of time the blade is in contact with themedical device ranges from about 1 second to about 3 seconds. In stillfurther embodiments, the amount of time the blade is in contact with themedical device is about 2 seconds.

In embodiments, the knife blade may be shaped substantially into arectangle shape, a square shape, a circle shape, a flat shape, anoctagonal shape, a triangle shape, a star shape, a spade shape, an arrowshape, a key shape and an elliptical shape. In some embodiments, thecurvature of the knife blade is substantially concave or substantiallyconvex.

In practice, the medical device passes in front of the converter 62which includes the horn 66 and the anvil 70, then using ultrasonicenergy at various frequencies and signal amplitudes cuts the material toa geometry. In embodiments, the medical device passes in front ofconverter 62 via motorized slide 74 which is configured and dimensionedto hold gripper 70 and camera 72 thereon. In certain embodiments, themedical device passes in front of converter 62, via a mechanical feedingmechanism with the medical device held tightly around two spools on eachside of the apparatus (not shown). In other embodiments, the medicaldevice passes in front of converter 62 via human manipulation of themedical device.

Still referring to FIG. 9, the apparatus 60 includes a converter 62coupled to a horn 66 which operatively moves along a straight line X-Yplane via ultrasonic vibrational energy. The horn 66 includes a bladewhich contacts a surface of the medical device at an angle so as to format least one barb on the medical device. The blade is appropriatelypositioned to contact the medical device via knife positioning slide 80.After each barb is formed, the medical device is moved in a linearmotion on a X-Y plane via motorized slide 74 a specified length to allowanother barb to be formed thereon. In embodiments, the medical device ismoved in a X-Z plane via motorized slide 74 a specified length to form abarb thereon. In further embodiments, the medical device is moved in aY-Z plane via motorized slide 74 a specified length to form a barbthereon. In alternative embodiments, the medical device is moved in acircular manner via rotational motor 76 to form a barb at a specifiedposition. In embodiments, the medical device is moved in both arotational and x-z plane rotation.

In practice, the barbs 12 are formed as either the knife blade or rotaryblade (not shown) contacts the outer surface of the medical device. Theblade may be urged into contact with the surface of the medical device,for example, by a reciprocating actuator in a straight line X-Y plane.It is contemplated, however, that in alternative embodiments, the blademay be held fixed and the medical device may be urged toward the blade.The blade makes contact with the surface of the medical device at anangle relative thereto such that the combined action of the movement ofthe blade into contact with the medical device surface and theultrasonic vibration of the knife forms the desired barb. Advance slide78 then moves the medical device after every cut a specified incrementfor the desired spacing of the barbs.

Ultrasonic energy may transfer heat to the medical device as it isforming the barbs thereon. Depending on the amplitude, the ultrasonicfrequency may cause melting of medical device if the blades are left topenetrate medical device throughout the full wave cycle. To prevent thisfrom occurring, in some embodiments, the application of ultrasonicenergy is discontinued at some point prior to withdrawal of the bladesfrom contact of the medical device. In other embodiments, this methodmay be used to vary the angle and the depth of the cut as indicatedabove with respect to the increase or decrease of the amplitude.

In some embodiments, barbs may be formed by making acute angular cutsdirectly into the elongated body of the medical device, with cutportions pushed outwardly and separated from the elongated body of themedical device. The depth of the barbs thus formed in the elongated bodymay depend on the diameter of the material and the depth of the cut.

In some embodiments, a suitable device for cutting a plurality ofaxially spaced barbs on the exterior of an elongated body of a medicaldevice may use a gripper as a cutting bed, a cutting bed vise, a cuttingtemplate, and a converter and horn as the blade assembly to perform thecutting. In operation, the cutting device has the ability to produce aplurality of axially spaced barbs in the same or random configurationand at different angles in relation to each other.

In other embodiments, the barbs may be arranged on a first portion of alength of the elongated body of the medical device to allow movement ofa first end of the medical device through tissue in one direction, whilebarbs on a second portion of the length of the elongated body of themedical device may be arranged to allow movement of the second end ofthe medical device in an opposite direction.

The barbs can be arranged in any suitable pattern, for example, helical,spiral, linear, or randomly spaced. The pattern may be symmetrical orasymmetrical. Barbs may be arranged around the entire circumference ofan elongated body of a medical device, or a portion thereof. Further,barbs may be arranged over the entire length of an elongated body, oronly through a portion or portions thereof. The number, configuration,spacing and surface area of the barbs can vary depending upon the tissuein which the medical device is used, as well as the composition andgeometry of the material utilized to form the medical device. Inembodiments, the barbs are positioned in a non-overlappingcorkscrew-like pattern around the circumference of an elongated body.Additionally, the proportions of the barbs may remain relativelyconstant while the overall length of the barbs and the spacing of thebarbs may be determined by the tissue being connected. For example, ifthe medical device is to be used to connect the edges of a wound in skinor tendon, the barbs may be made relatively short and more rigid tofacilitate entry into this rather firm tissue. Alternatively, if themedical device is intended for use in fatty tissue, which is relativelysoft, the barbs may be made longer and spaced further apart to increasethe ability of the barbs to grip the soft tissue.

The surface area of the barbs can also vary. For example, fuller-tippedbarbs can be made of varying sizes designed for specific surgicalapplications. For joining fat and relatively soft tissues, larger barbsmay be desired, whereas smaller barbs may be more suitable forcollagen-dense tissues. In some embodiments, a combination of large andsmall barbs within the same structure may be beneficial, for examplewhen a suture is used in tissue repair with differing layer structures.In particular embodiments, a single directional suture may have bothlarge and small barbs; in other embodiments a bi-directional suture mayhave both large and small barbs.

Medical device 100 in accordance with the present disclosure may beformed of absorbable materials, non-absorbable materials, andcombinations thereof. More particularly, the medical device may beformed of an absorbable material selected from the group consisting ofpolyesters, polyorthoesters, polymer drugs, polydroxybutyrates,dioxanones, lactones, proteins, cat gut, collagens, carbonates,homopolymers thereof, copolymers thereof, and combinations thereof. Inother embodiments, suitable absorbable materials which may be utilizedto form the medical device include natural collagenous materials orsynthetic resins including those derived from alkylene carbonates suchas trimethylene carbonate, tetramethylene carbonate, and the like,caprolactone, glycolic acid, lactic acid, glycolide, lactide,homopolymers thereof, copolymers thereof, and combinations thereof. Insome embodiments, glycolide and lactide based polyesters, especiallycopolymers of glycolide and lactide, may be utilized to form the medicaldevice of the present disclosure. In other embodiments, a medical deviceof the present disclosure may be formed from dissolvable metals, such asmagnesium.

In embodiments, suitable materials which may be utilized to form themedical devices in accordance with the present disclosure includehomopolymers, copolymers, and/or blends possessing glycolic acid, lacticacid, glycolide, lactide, dioxanone, trimethylene caprolactone, andvarious combinations of the foregoing. For example, in some embodiments,a copolymer of glycolide and trimethylene carbonate may be utilized.Methods for forming such copolymers are within the purview of thoseskilled in the art and include, for example, the methods disclosed inU.S. Pat. Nos. 4,300,565 and 5,324,307, the entire disclosures of eachor which are incorporated by reference herein. Suitable copolymers ofglycolide and trimethylene carbonate may possess glycolide in amountsfrom about 60% to about 75% by weight of the copolymer, in embodiments,from about 65% to about 70% by weight of the copolymer, with thetrimethylene carbonate being present in amounts from about 25% to about40% by weight of the copolymer, in embodiments, from about 30% to about35% by weight of the copolymer.

Other suitable materials include copolymers of lactide and glycolide,with lactide present in an amount from about 6% to about 12% by weightof the copolymer and glycolide being present in amounts from about 88%to about 94% by weight of the copolymer. In some embodiments, lactide ispresent from about 7% to about 11% by weight of the copolymer withglycolide being present in amounts from about 89% to about 98% by weightof the copolymer. In some other embodiments, lactide is present in anamount of about 9% by weight of the copolymer with the glycolide beingpresent in an amount of about 91% by weight of the copolymer.

In embodiments, suitable materials for forming barbed medical devicesaccording to the present disclosure include, in embodiments, copolymersof glycolide, dioxanone, and trimethylene carbonate. Such materials mayinclude, for example, copolymers possessing glycolide in amounts fromabout 55% to about 65% by weight of the copolymer, in embodiments, fromabout 58% to about 62% by weight of the copolymer, in some embodiments,about 60% by weight of the copolymer; dioxanone in amounts from about10% to about 18% by weight of the copolymer, in embodiments, from about12% to about 16% by weight of the copolymer, in some embodiments about14% by weight of the copolymer; and trimethylene carbonate in amountsfrom about 17% to about 35% by weight of the copolymer, in embodiments,from about 22% to about 30% by weight of the copolymer, in someembodiments, about 26% by weight of the copolymer.

Other suitable materials include a copolymer of glycolide, lactide,trimethylene carbonate, and ε-caprolactone may be utilized to formmedical devices in accordance with the present disclosure. Suchmaterials may include, for example, a random copolymer possessingcaprolactone in amounts from about 14% to about 20% by weight of thecopolymer, in embodiments, from about 16% to about 18% by weight of thecopolymer, in some embodiments, about 17% by weight of the copolymer;lactide in amounts from about 4% to about 10% by weight of thecopolymer, in embodiments, from about 6% to about 8% by weight of thecopolymer, in some embodiments about 7% by weight of the copolymer;trimethylene carbonate in amounts from about 4% to about 10% by weightof the copolymer, in embodiments from about 6% to about 8% by weight ofthe copolymer, in some embodiments about 7% by weight of the copolymer;and glycolide in amounts from about 60% to about 78% by weight of thecopolymer, in embodiments, from about 66% to about 72% by weight of thecopolymer, in some embodiments about 69% by weight of the copolymer.

Barbed medical devices fabricated from an absorbable material inaccordance with the present disclosure maintain their structuralintegrity after implantation (e.g., about 80% of original strength) fora period of time, depending on the various processing parameters and theparticular copolymer used. Such characteristics include, for example,the components of the copolymer, including both the monomers utilized toform the copolymer and any additives thereto, as well as the processingconditions (e.g., rate of copolymerization reaction, temperature forreaction, pressure, etc.), and any further treatment of the resultingcopolymers, i.e., coating, sterilization, etc.

The formation of barbs on an absorbable medical device may alter thedegradation characteristics of the device. For example, the formation ofbarbs on a suture body may be utilized to alter the degradation time ofa suture in accordance with the present disclosure as described in U.S.patent application Ser. No. 11/556,002 filed on Nov. 2, 2006 entitled“Long Term Bioabsorbable Barbed Sutures”, the entire contents of whichare incorporated by reference herein.

For non-absorbable barbed medical devices constructed in accordance withthe present disclosure, suitable non-absorbable materials which may beutilized to form the medical device include polyolefins, such aspolyethylene, polypropylene, copolymers of polyethylene andpolypropylene, and blends of polyethylene and polypropylene; polyamides(such as nylon); polyamines; polyimines; polyesters such as polyethyleneterephthalate; fluoropolymers such as polytetrafluoroethylene;polyether-esters such as polybutesters; polytetramethylene ether glycol;1,4-butanediol; polyurethanes; and combinations thereof. Thepolypropylene can be isotactic polypropylene or a mixture of isotacticand syndiotactic or atactic polypropylene. In other embodiments,non-absorbable materials may include silk, cotton, linen, carbon fibers,and the like. In yet other embodiments, non-absorbable materials forforming a medical device of the present disclosure include metals, suchas titanium, stainless steel and alloys thereof.

Filaments and fibers used for forming a medical device of the presentdisclosure may be formed using any technique within the purview of thoseskilled in the art, such as, for example, extrusion, molding and/orsolvent casting.

In one embodiment, compound barbs are formed on a monofilament suture. Abarbed monofilament suture may be used in embodiments where higherstrength and longer absorption and strength profiles are desired. Thecompound barb monofilament sutures may be favored, for example, indermal application where there is an increased risk of infection.

In some embodiments, medical devices of the present disclosure mayinclude a yarn made of more than one filament, which may containmultiple filaments of the same or different materials. Where the medicaldevices are made of multiple filaments, the medical device can be madeusing any known technique such as, for example, braiding, weaving orknitting. The filaments may also be combined to produce a non-wovensuture. The filaments themselves may be drawn, oriented, crinkled,twisted, commingled or air entangled to form yarns as part of the sutureforming process.

Barbs may be formed on staples in accordance with the presentdisclosure. As illustrated in FIG. 12, staple 800 include a crown 810connecting a pair of elongated bodies or legs 840. The crown is shown asa straight member, but may be formed in any shape capable ofinterconnecting the legs 840, such as an apex. The legs 840 extendsubstantially perpendicular from the crown, but in alternate embodimentsmay extend from the crown at an angle therefrom. Barbs 820 are formed onlegs 840. Barb angles, geometries, and methods for creating barbsinclude those referenced herein.

The staple 800 may be deployed and deformed into the typical crimped,“B” shape via a delivery device or alternatively, the barbs 820 of legs840 can be deployed in the original configuration as shown in FIG. 12because once deployed, the barbs 820 anchor into tissue therebyresisting deformation and enhancing the tissue pull-apart strength. Thetissue pull-apart strength is dependent upon such factors as the angleof the barbs and the number of barbs per staple leg. The direction ofthe barbs also ensures that the staple will penetrate and properlyanchor into tissue. Moreover, the diameter required of the staple tomeet the holding strength is reduced compared to that of a typicalunbarbed staple. Thus, the holding strength of the barbed staple can bemade to match that of the crimped unbarbed staple, thereby eliminatingthe need for an anvil on the stapler and preventing the possibility ofmisfires, incomplete crimping, or overcrimping which may occur withconventional delivery devices.

In other embodiments, compound barb medical devices may include othermedical devices such as braided sutures, surgical fibers, anchors, slitsheets, ribbons, tapes, meshes, stents, scaffolds, pledgets, andvascular grafts.

Once the medical device is barbed, it can be sterilized by any meanswithin the purview of those skilled in the art.

In embodiments, the barbed medical device, in whole or in part (e.g.,the medical device body, barbs, and/or portions thereof), may beconstructed using shape memory polymers which are capable of adopting ashape in vivo suitable for adhering tissue, assisting in securing thebarbed device, or affixing another surgical device, such as a mesh, totissue. Shape memory polymeric materials utilized to form a barbedmedical device of the present disclosure possess a permanent shape and atemporary shape. In embodiments, the temporary shape is of aconfiguration which enhances the ability of the surgeon to introduce themedical device into a patient's body. The permanent shape, which isassumed in vivo upon application of energy, such as heat or light, is ofa configuration which enhances the retention of the medical device intissue and/or adhesion of a surgical device to tissue.

Shape memory polymers are a class of polymers that, when formed into anobject such as a suture or staple, can be temporarily deformed bymechanical force and then caused to revert back to an original shapewhen stimulated by energy. Shape memory polymers exhibit shape memoryproperties by virtue of at least two phase separated microdomains intheir microstructure. The first domain is composed of hard, covalentlycross-linked or otherwise chain motion-limiting structures, which act asanchors to retain the object's original shape. The second domain is aswitchable soft structure, which can be deformed and then fixed toobtain a secondary or temporary shape.

In the case of heat stimulated shape memory polymers, a transitiontemperature (T_(Trans)) exists at which the shape change occurs duringheating. The shape memory polymers can thus be tailored by alteringmaterial properties at the molecular level and by varying processingparameters. An object's primary shape may be formed with heat andpressure at a temperature at which the soft domains are flexible and thehard domains are not fully formed. The object may then be cooled so thatthe hard domains are more fully formed and the soft domains becomerigid. The secondary or temporary shape can be formed by mechanicallydeforming the object, which is most readily accomplished at atemperature approaching or above T_(Trans). Mechanical stressesintroduced into the object are then locked into place by cooling theobject to temperatures below T_(Trans), so that the soft segmentssolidify to a rigid state. Once the object is heated to T>T_(Trans), thesoft segments soften and relax back to their original configuration andthe object returns to its primary or original shape, sometimes referredto herein, as its permanent shape. The temperature at which a shapememory material reverts to its permanent shape may be referred to, inembodiments, as its permanent temperature (T_(perm)).

Polymers possessing shape memory properties which may be used toconstruct barbed medical devices disclosed herein include, for example,synthetic materials, natural materials (e.g., biological) andcombinations thereof, which may be biodegradable and/ornon-biodegradable. As used herein, the term “biodegradable” includesboth bioabsorbable and bioresorbable materials. By biodegradable, it ismeant that the materials decompose, or lose structural integrity underbody conditions (e.g., enzymatic degradation, hydrolysis) or are brokendown (physically or chemically) under physiologic conditions in the body(e.g., dissolution) such that the degradation products are excretable orabsorbable by the body.

Suitable non-degradable materials which may possess shape memoryproperties include, but are not limited to, polyolefins such aspolyethylene (including ultra high molecular weight polyethylene) andpolypropylene including atactic, isotactic, syndiotactic, and blendsthereof; polyethylene glycols; polyethylene oxides; ultra high molecularweight polyethylene; copolymers of polyethylene and polypropylene;polyisobutylene and ethylene-alpha olefin copolymers; fluorinatedpolyolefins such as fluoroethylenes, fluoropropylenes, fluoroPEGs, andpolytetrafluoroethylene; polyamides such as nylon, Nylon 6, Nylon 6,6,Nylon 6,10, Nylon 11, Nylon 12, and polycaprolactam; polyamines;polyimines; polyesters such as polyethylene terephthalate, polyethylenenaphthalate, polytrimethylene terephthalate, and polybutyleneterephthalate; polyethers; polytetramethylene ether glycol;polybutesters, including copolymers of butylene terephthalate andpolytetramethylene ether glycol; 1,4-butanediol; polyurethanes; acrylicpolymers; methacrylics; vinyl halide polymers and copolymers such aspolyvinyl chloride; polyvinyl alcohols; polyvinyl ethers such aspolyvinyl methyl ether; polyvinylidene halides such as polyvinylidenefluoride and polyvinylidene chloride; polychlorofluoroethylene;polyacrylonitrile; polyaryletherketones; polyvinyl ketones; polyvinylaromatics such as polystyrene; polyvinyl esters such as polyvinylacetate; copolymers of vinyl monomers with each other and olefins suchas ethylene-methyl methacrylate copolymers; acrylonitrile-styrenecopolymers; ABS resins; ethylene-vinyl acetate copolymers; alkyd resins;polycarbonates; polyoxymethylenes; polyphosphazine; polyimides; epoxyresins; aramids; rayon; rayon-triacetate; spandex; silicones; andcopolymers and combinations thereof. Additionally, non-biodegradablepolymers and monomers may be combined with each other.

Suitable bioabsorbable polymers which may possess shape memoryproperties include, but are not limited to, aliphatic polyesters;polyamides; polyamines; polyalkylene oxalates; poly(anhydrides);polyamidoesters; copoly(ether-esters); poly(carbonates) includingtyrosine derived carbonates; poly(hydroxyalkanoates) such aspoly(hydroxybutyric acid), poly(hydroxyvaleric acid), andpoly(hydroxybutyrate); polyimide carbonates; poly(imino carbonates) suchas poly (bisphenol A-iminocarbonate and the like); polyorthoesters;polyoxaesters including those containing amine groups; polyphosphazenes;poly (propylene fumarates); polyurethanes; polymer drugs such aspolydiflunisol, polyaspirin, and protein therapeutics; biologicallymodified (e.g., protein, peptide) bioabsorbable polymers; andcopolymers, block copolymers, homopolymers, blends, and combinationsthereof.

Suitable aliphatic polyesters may include, but are not limited to,homopolymers and copolymers of lactide (including lactic acid, D-,L- andmeso lactide); glycolide (including glycolic acid);epsilon-caprolactone; p-dioxanone (1,4-dioxan-2-one); trimethylenecarbonate (1,3-dioxan-2-one); alkyl derivatives of trimethylenecarbonate; Δ-valerolactone; β-butyrolactone; γ-butyrolactone;ε-decalactone; hydroxybutyrate; hydroxyvalerate; 1,4-dioxepan-2-one(including its dimer 1,5,8,12-tetraoxacyclotetradecane-7,14-dione);1,5-dioxepan-2-one; 6,6-dimethyl-1,4-dioxan-2-one; 2,5-diketomorpholine;pivalolactone; α, α diethylpropiolactone; ethylene carbonate; ethyleneoxalate; 3-methyl-1,4-dioxane-2,5-dione;3,3-diethyl-1,4-dioxan-2,5-dione; 6,8-dioxabicycloctane-7-one; andpolymer blends and copolymers thereof.

Other suitable biodegradable polymers include, but are not limited to,poly(amino acids) including proteins such as collagen (I, II and III),elastin, fibrin, fibrinogen, silk, and albumin; peptides includingsequences for laminin and fibronectin (RGD); polysaccharides such ashyaluronic acid (HA), dextran, alginate, chitin, chitosan, andcellulose; glycosaminoglycan; gut; and combinations thereof. Collagen asused herein includes natural collagen such as animal derived collagen,gelatinized collagen, or synthetic collagen such as human or bacterialrecombinant collagen.

Additionally, synthetically modified natural polymers such as celluloseand polysaccharide derivatives, including alkyl celluloses, hydroxyalkylcelluloses, cellulose ethers, cellulose esters, nitrocelluloses, andchitosan may be utilized. Examples of suitable cellulose derivativesinclude methyl cellulose, ethyl cellulose, hydroxypropyl cellulose,hydroxypropyl methyl cellulose, hydroxybutyl methyl cellulose, celluloseacetate, cellulose propionate, cellulose acetate butyrate, celluloseacetate phthalate, carboxymethyl cellulose (CMC), cellulose triacetate,and cellulose sulfate sodium salt. These may be collectively referred toherein, in embodiments, as “celluloses.”

In embodiments, combinations of both degradable and non-degradablematerials, including those having shape memory characteristics, may beutilized.

In embodiments, the shape memory polymer may be a copolymer of twocomponents with different thermal characteristics, such as oligo(epsilon-caprolactone) dimethacrylates and butyl acrylates, includingpoly(epsilon-caprolactone) dimethacrylate-poly(n-butyl acrylate), or adiol ester and an ether-ester diol such as oligo (epsilon caprolactone)diol/oligo (p-dioxanone) diol copolymers. These multi-block oligo(epsilon-caprolactone) diol/oligo (p-dioxanone) diol copolymers possesstwo block segments: a “hard” segment and a “switching” segment linkedtogether in linear chains. Such materials are disclosed, for example, inLendlein, “Shape Memory Polymers-Biodegradable Sutures,” MaterialsWorld, Vol. 10, no. 7, pp. 29-30 (July 2002), the entire disclosure ofwhich is incorporated by reference herein.

In other embodiments, blends of bioabsorbable materials may be utilizedincluding, but not limited to, urethanes blended with lactic acid and/orglycolic acid, homopolymers thereof or copolymers thereof, and acrylatesblended with caprolactones such as polycaprolactone dimethacrylatepoly(butyl acrylate) blends, and combinations thereof.

Other examples of suitable shape memory polymers and means for formingpermanent and temporary shapes therewith are set forth in Lendlein etal., “Shape memory polymers as stimuli-sensitive implant materials,”Clinical Hemorheology and Microcirculation, 32 (2005) 105-116, Lendleinet al., “Biodegradable, Elastic Shape memory Polymers for PotentialBiomedical Applications,” Science, Vol. 269 (2002) 1673-1676, andLendlein et al., “Shape-Memory Polymers,” Angew. Chem. Int. Ed., 41(2002) 2035-2057, the entire disclosures of each of which areincorporated by reference herein.

Table 1 below further illustrates compositions which demonstrate shapememory effects. The block copolymers of each composition are in annealedwire format, the proposed soft and hard segments, and the glasstransition temperature (T_(g)), having been measured by differentialscanning calorimetry which is equal to T_(Trans).

TABLE 1 T_(g) (T_(Trans)) Composition (mol %) Soft Domain Hard Domain [°C.] 15% Polydioxanone Polydioxanone and Crystalline 54 85% Poly(L-lactide) Amorphous Polylactide Polylactide 20% PolydioxanonePolydioxanone and Crystalline 45 80% Poly (L-lactide) AmorphousPolylactide Polylactide 15% Trimethylene Trimethylene Crystalline 54Carbonate Carbonate and Polylactide 85% Poly (L-lactide) AmorphousPolylactide 20% Trimethylene Trimethylene Crystalline 55 CarbonateCarbonate and Polylactide 80% Poly (L-lactide) Amorphous Polylactide

The copolymers in Table 1 may undergo a partial shift when approachingT_(g) and T_(Trans) may be depressed when the materials are in aqueoussolution. Since these polymers degrade by water absorption and bulkhydrolysis, water molecules entering the polymer matrices may act asplasticizers, causing the soft segments to soften at lower temperaturesthan in dry air. Thus, polymers exhibiting T_(Trans) depression inaqueous solution may maintain a temporary shape through temperatureexcursions in the dry state, such as during shipping and storage, andshape shift to its permanent shape at body temperatures uponimplantation.

Thus, in embodiments, the shape memory polymer may include a blockcopolymer of polydioxanone and polylactide with the polydioxanonepresent in an amount from about 5 mol % to about 20 mol % of thecopolymer, in embodiments from about 15 mol % to about 19 mol % of thecopolymer, and the polylactide present in an amount from about 80 mol %to about 95 mol % of the copolymer, in embodiments from about 81 mol %to about 85 mol % of the copolymer. In other embodiments, the shapememory polymer may include a block copolymer of trimethylene carbonateand polylactide, with the trimethylene carbonate present in an amountfrom about 5 mol % to about 20 mol % of the copolymer, in embodimentsfrom about 15 mol % to about 19 mol % of the copolymer, and thepolylactide may be present in an amount from about 80 mol % to about 95mol % of the copolymer, in embodiments from about 81 mol % to about 85mol % of the copolymer.

It is envisioned that T_(Trans) may be tailored by changing blocksegment molar ratios, polymer molecular weight, and time allowed forhard segment formation. In embodiments, T_(Trans) may be tailored byblending various amounts of low molecular weight oligomers of the softsegment domain into the copolymer. Such oligomers may segregate to softdomains and act as plasticizers to cause a downward shift in T_(Trans).

Additionally, the copolymers forming the barbed medical devices of thepresent disclosure may include emulsifying agents, solubilizing agents,wetting agents, taste modifying agents, plasticizers, active agents,water soluble inert fillers, preservatives, buffering agents, coloringagents, and stabilizers. Addition of a plasticizer to the formulationcan improve flexibility. The plasticizer or mixture of plasticizers maybe polyethylene glycol, glycerol, sorbitol, sucrose, corn syrup,fructose, dioctyl-sodium sulfosuccinate, triethyl citrate, tributylcitrate, 1,2-propylenglycol, mono-, di- or triacetates of glycerol, ornatural gums.

In some embodiments, crystalline degradable salts or minerals may beadded to the block copolymer compositions to create polymer compositeswhich may improve shape memory properties. An example of such acomposite using polylactide homopolymer and crystalline hydroxyapatiteis described in Zheng et al., “Shape memory properties of poly(D,L-lactide/hydroxyapatite composites,” Biomaterials, 27 (2006)4288-4295, the entire disclosure of which is incorporated by referenceherein.

Other shape memory materials, including shape memory metals and metalalloys such as Nitinol, may also be used to form the medical devices ofthe present disclosure.

In embodiments, a molding process may be utilized to produce a barbedmedical device in accordance with the present disclosure. Plasticmolding methods are within the purview of those skilled in the art andinclude, but are not limited to, melt molding, solution molding, and thelike. Injection molding, extrusion molding, compression molding andother methods can also be used as the melt molding technique. Onceplaced in the mold with the proper dimensions and configuration, thepolymeric material used to form the medical device may be heated to asuitable temperature, such as the permanent temperature (T_(perm)) whichmay, in embodiments, be the melting temperature of the shape memorypolymeric material utilized to form the medical device. Heating of themedical device may be at suitable temperatures including, for example,from about 40° C. to about 180° C., in embodiments from about 80° C. toabout 150° C., for a period of time of from about 2 minutes to about 60minutes, in embodiments from about 15 minutes to about 20 minutes, toobtain the permanent shape and dimensions.

The temperature for deformation treatment of the medical device moldedwith a previously memorized shape is one that makes possible readydeformation without producing cracks and should not exceed thetemperature adopted for the shape memorization (e.g., T_(perm)).Deformation treatment at a temperature exceeding that for the originalshape memorization may cause the object to memorize/program a newdeformed shape.

After the medical device with the desired shape has been formed, themedical device may be deformed above T_(trans) to obtain an alternate,temporary shape. Suitable temperatures for deformation will varydepending on the shape memory polymer utilized, but generally may beabove the transition temperature of the polymer (T_(trans)), but belowthe T_(perm). In embodiments, the shape memory polymer may be cooledfrom its T_(perm) to a lower temperature which remains above theT_(trans) and deformed, in embodiments by hand and/or mechanical means.In other embodiments, the medical device may be deformed at roomtemperature (about 20° C. to about 25° C.) to obtain its temporaryshape, although the temperature may differ depending upon the particularpolymer employed. The medical device may then be cooled to a temperaturebelow the T_(trans) of the material utilized to form the medical device,at which time the medical device of the present disclosure is ready foruse. As the T_(trans) is usually greater than room temperature, inembodiments cooling to room temperature may be sufficient to lock in thetemporary shape.

There are no particular limitations on the manner in which thedeformation can be achieved. Deformation can be achieved either by handor by means of a suitable device selected to provide the desiredtemporary configuration to the medical device.

In order to keep the shape of the medical device in its temporary shape,the shape memory barbed medical device of the present disclosure shouldbe stored at a temperature which will not cause a transition to thepermanent shape. In embodiments, the shape memory medical device may bestored in a refrigerator.

In embodiments, the shape memory polymeric materials of the presentdisclosure may be compressed or expanded into temporary forms that aresmaller or larger in diameter than their permanent shape.

The medical devices thus prepared recover their permanent shape uponapplication of energy, such as on heating, either by placement in apatient's body, or the addition of exogenous heat at a prescribedtemperature, in embodiments above the T_(trans) of the shape memorypolymer utilized. As the medical devices of the present disclosure areutilized in a living body, heating with body heat (about 37° C.) ispossible. In such a case, the temperature for shape programming shouldbe as low as possible and the recovery of the permanent may occur fairlyslowly. In embodiments, recovery of the permanent shape may occur fromabout 1 second to about 5 seconds after insertion into tissue.

In embodiments, the shape memory polymer medical device is a barbedsuture as described above. The suture may be barbed and then annealednear its crystallization temperature to program a permanent shape to thesuture and/or its barbs. For example, the permanent shape of the suturemay include the barbs extending away from the elongated body. Atemporary shape may then be imparted to the suture. For example, thebarbed suture may be fed through a tube having an inner diametersufficiently small to compress the barbs against the suture body. Thetube may then be heated above the transition temperature of the shapememory polymeric material to soften the barbs, and then the tube andsuture may be cooled to set the temporary shape. The suture may then beremoved from the tube with the barbs approximated, or in alignment, withthe elongated body. After deployment in the body, the barbs will extendback to their primary extended shape, thereby limiting movement of thesuture within tissue. In other embodiments, the shape memory medicaldevice may be a barbed staple as also described above.

However, in some embodiments a higher shape memory temperature may bedesirable in order to make the shape recover at a slightly highertemperature than body temperature. Thus, in some cases, releasing themedical device from deformation to recover the permanent shape can beachieved by heating. On heating at a temperature of from about 30° C. toabout 50° C., in embodiments from about 39° C. to about 43° C., thetemporary shape may be released and the permanent shape recovered. Thehigher the temperature for heating, the shorter the time required forrecovery of the permanent shape. The means for this heating is notlimited. Heating can be accomplished by using a gas or liquid heatingmedium, heating devices, ultrasonic waves, electrical induction, and thelike. Of course, in an application involving a living body, care must betaken to utilize a heating temperature which will not cause burns.Examples of liquid heating media include, physiological saline solution,alcohol, combinations thereof, and the like.

Similarly, in other embodiments, electrically active polymers, alsoknown as electroactive polymers, which can alter their configurationupon application of electricity, may be utilized to fashion medicaldevices in accordance with the present disclosure. Suitable examples ofelectroactive polymers include poly(aniline), substitutedpoly(aniline)s, polycarbazoles, substituted polycarbazoles, polyindoles,poly(pyrrole)s, substituted poly(pyrrole)s, poly(thiophene)s,substituted poly(thiophene)s, poly(acetylene)s, poly(ethylenedioxythiophene)s, poly(ethylenedioxypyrrole)s, poly(p-phenylenevinylene)s, and the like, or combinations including at least one of theforegoing electroactive polymers. Blends or copolymers or composites ofthe foregoing electroactive polymers may also be used.

Similar to the change in shape which a shape memory material may undergoupon the application of energy, such as heat, in embodiments anelectroactive polymer may undergo a change in shape upon the applicationof electricity from a low voltage electrical source (such as a battery).Suitable amounts of electricity which may be applied to effect suchchange will vary with the electroactive polymer utilized, but can befrom about 5 volts to about 30 volts, in embodiments from about 10 voltsto about 20 volts. The application of electricity will result in themedical device constructed of the electroactive polymer changing itsshape from a temporary shape to its permanent shape.

While an electroactive polymer does not have the same permanent shapeand temporary shape as those terms are described above with respect toshape memory polymers, as used herein the term “permanent shape” asapplied to an electroactive polymer means, in embodiments, the shape theelectroactive polymer adopts upon the application of electricity, andthe term “temporary shape” as applied to an electroactive polymer means,in embodiments, the shape of the electroactive polymer adopts in theabsence of electricity.

In some embodiments, the sutures may include metals (e.g. steel anddegradable magnesium), metal alloys or the like.

As used herein, the terms “fibers”, “filaments” and “yarns” each may beused to construct sutures or other devices, in whole or in part. Theterm “fibers,” in this context, are generally used to designate naturalor synthetic structures that have a length approximately 3 orders ofmagnitude greater than their diameter or width. The term “filaments” aretypically used to describe “fibers” of indefinite or extreme length, and“yarns” as a generic term for a continuous strand of twisted oruntwisted “fibers” or “filaments” in a form suitable for knitting,weaving, braiding or otherwise intertwining.

In embodiments, sutures of the present disclosure may possess acore/sheath configuration, fibers may possess a core/sheathconfiguration, yarns may possess a core/sheath configuration, or both.Any material described herein, including the shape memory materialsdescribed above, may be utilized to form the core, the sheath, or both.

Sutures of the present disclosure may be monofilament or multifilament(e.g. braided). Methods for making sutures from these suitable materialsare within the purview of those skilled in the art (e.g. extrusion andmolding). The filaments may be combined to create a multifilament sutureusing any technique within the purview of one skilled in the art such ascommingling, twisting, braiding, weaving, entangling, and knitting. Forexample, filaments may be combined to form a yarn or they may bebraided. In another example, filaments may be combined to form a yarnand then those multifilament yarns may be braided. Those skilled in theart reading this disclosure will envision other ways in which filamentsmay be combined. Fibers may also be combined to produce a non-wovenmultifilament large diameter suture. In certain embodiments, amultifilament structure useful in forming a device according to thepresent disclosure may be produced by braiding. The braiding can be doneby any method within the purview of those skilled in the art. Forexample, braid constructions for sutures and other medical devices aredescribed in U.S. Pat. Nos. 5,019,093; 5,059,213; 5,133,738; 5,181,923;5,226,912; 5,261,886; 5,306,289; 5,318,575; 5,370,031; 5,383,387;5,662,682; 5,667,528; and 6,203,564; the entire disclosures of each ofwhich are incorporated by reference herein. Furthermore, the device ofthe present disclosure may include portions which are monofilament andportions which are multifilament. In some embodiments, the proximal endof the elongate body may be a multifilament and the looped portion (loopportion described below) may be a monofilament.

Medical devices in accordance with the present disclosure may be coatedor impregnated with one or more synthetic or natural polymers e.g.,bioactive agents which accelerate or beneficially modify the healingprocess when the medical device is applied to a wound or surgical site.In certain embodiments, the coating may be formed from absorbablepolymers selected from the group consisting of lactones, carbonates,polyorthoesters, hydroxyalkoanates, hydroxybutyrates, bioactive agents,polyanhydrides, silicone, vinyl polymers, high molecular weight waxesand oils, natural polymers, proteins, polysaccharides, suspendableparticulates, dispersible particulates, microspheres, nanospheres, rods,homopolymers thereof, copolymers thereof, and combinations thereof.

Suitable bioactive agents include, for example, biocidal agents,antimicrobial agents, antibiotics, anti-proliferatives, medicants,growth factors, anti-clotting agents, clotting agents, analgesics,anesthetics, anti-inflammatory agents, wound repair agents and the like,chemotherapeutics, biologics, protein therapeutics, monoclonal orpolyclonal antibodies, DNA, RNA, peptides, polysaccharides, lectins,lipids, probiotics, diagnostic agents, angiogenics, anti-angiogenicdrugs, polymeric drugs, and combinations thereof.

Bioactive agents include substances which are beneficial to the animaland tend to promote the healing process. For example, a suture can beprovided with a bioactive agent that will be deposited at the suturedsite. The bioactive agent can be chosen for its antimicrobialproperties, capability for promoting wound repair and/or tissue growth,or for specific indications such as thrombosis. In embodiments,combinations of such agents may be applied to the medical device of thepresent disclosure after formation of the barbs.

The term “antimicrobial agent” as used herein includes an agent which byitself or through the assistance of the immune system, helps the bodydestroy or resist microorganisms which may be pathogenic. Anantimicrobial agent includes antibiotics, antiseptics, quorum sensingblockers, antifungals, anti-virals, surfactants, metal ions,antimicrobial proteins and peptides, antimicrobial polysaccharides,disinfectants and combinations thereof. Antimicrobial agents which areslowly released into the tissue can be applied in this manner to aid incombating clinical and sub-clinical infections in a surgical or traumawound site. In embodiments, suitable antimicrobial agents may be solublein one or more solvents.

In embodiments, the following anti-microbial agents may be used alone orin combination with other bioactive agents described herein: ananthracycline, doxorubicin, mitoxantrone, a fluoropyrimidine,5-fluorouracil (5-FU), a folic acid antagonist, methotrexate,mitoxantrone, quorum sensing blocker, brominated or halogenatedfuranones, a podophylotoxin, etoposide, camptothecin, a hydroxyurea, aplatinum complex, cisplatin, doxycycline, metronidazole,trimethoprim-sulfamethoxazole, rifamycins like rifampin, a fourthgeneration penicillin (e.g., a ureidopenicillin a carboxypenicillin,meziocillin, piperacillin, carbenicillin, and ticarcillin, and ananalogue or derivative thereof), a first generation cephalosporin (e.g.,cephazolin sodium, cephalexin, cefazolin, cephapirin, and cephalothin),a carboxypenicillin (e.g., ticarcillin), a second generationcephalosporin (e.g., cefuroxime, cefotetan, and cefoxitin), a thirdgeneration cephalosporin (e.g., naxcel, cefdinir, cefoperazone,ceftazidime, ceftriaxone, and cefotaxime), polyvinyl pyrrolidone (PVP),a fourth generation cephalosporin (e.g., cefepime), a monobactam (e.g.,aztreonam), a carbapenem (e.g., imipenem, ertapenem and meropenem), anaminoglycoside (e.g., streptomycin, gentamicin, tobramycin, andamikacin), an MSL group member (e.g., a macrolide, a long actingmacrolide, a lincosamide, a streptogramin, Erythromycin, Azithromycin,Clindamycin, Syneroid, clarithromycin, and kanamycin sulfate),tetracyclines (e.g., minocycline, fusidic acid, trimethoprim,metronidazole), a quinolone (e.g., ciprofloxacin, ofloxacin,gatifloxacin, moxifloxacin, levofloxacin, and trovafloxacin), a DNAsynthesis inhibitor (e.g., metronidazole), a sulfonamide (e.g.sulfamethoxazole, trimethoprim, including cefixime, spectinomycin,tetracycline, nitrofurantoin, polymyxin B, and neomycin sulfate),beta-lactam inhibitors like sulbactam, chloramphenicol, glycopeptideslike vancomycin, mupirocin, polyenes like amphotericin B, azoles likefluconazole, and other known antimicrobial agents known in the art.

Examples of chemotherapeutics which may be utilized include one or moreof the following: doxorubicin (Dox), paclitaxel (PTX), camptothecin(CPT), polyglutamate-PTX (CT-2103 or Xyotax),N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer, anthracycline,mitoxantrone, letrozole, anastrozole, epidermal growth factor receptorinhibitors, tyrosine kinase inhibitors, modulators of apoptosis,anthracycline antibiotics such as daunorubicin and doxorubicin,alkylating agents such as cyclophosphamide and melphalan,antimetabolites such as methotrexate and 5-fluorouracil, poly(ethyleneglycol) (PEG), poly(glutamic acid) (PGA), polysaccharides, monoclonalantibody and polymer-drug conjugates thereof, copolymers thereof andcombinations thereof.

Clotting agents which may be incorporated into a medical device of thepresent disclosure include one or more of the following: a fibrosingagent that promotes cell regeneration, a fibrosing agent that promotesangiogenesis, a fibrosing agent that promotes fibroblast migration, afibrosing agent that promotes fibroblast proliferation, a fibrosingagent that promotes deposition of extracellular matrix, a fibrosingagent that promotes tissue remodeling, a fibrosing agent that is adiverticular wall irritant, silk (such as silkworm silk, spider silk,recombinant silk, raw silk, hydrolyzed silk, acid-treated silk, andacylated silk), talc, chitosan, bleomycin or an analogue or derivativethereof, connective tissue growth factor (CTGF), metallic beryllium oran oxide thereof, copper, saracin, silica, crystalline silicates, quartzdust, talcum powder, ethanol, a component of extracellular matrix,oxidized cellulose, polysaccharides, collagen, fibrin, fibrinogen,poly(ethylene terephthalate), poly(ethylene-co-vinylacetate),N-carboxybutylchitosan, an RGD protein, a polymer of vinyl chloride,cyanoacrylate, crosslinked poly(ethylene glycol)-methylated collagen, aninflammatory cytokine, TGFβ, PDGF, VEGF, TNFa, NGF, GM-CSF, IGF-a, IL-1,IL-8, IL-6, a growth hormone, a bone morphogenic protein, a cellproliferative agent, dexamethasone, isotretinoin, 17-β-estradiol,estradiol, diethylstibesterol, cyclosporine a, all-trans retinoic acidor an analogue or derivative thereof, wool (including animal wool, woodwool, and mineral wool), cotton, bFGF, polyurethane,polytetrafluoroethylene, activin, angiopoietin, insulin-like growthfactor (IGF), hepatocyte growth factor (HGF), a colony-stimulatingfactor (CSF), erythropoietin, an interferon, endothelin-1, angiotensinII, bromocriptine, methylsergide, fibrosin, fibrin, an adhesiveglycoprotein, proteoglycan, hyaluronan, secreted protein acidic and richin cysteine (SPaRC), a thrombospondin, tenacin, a cell adhesionmolecule, dextran based particles, an inhibitor of matrixmetalloproteinase, magainin, tissue or kidney plasminogen activator, atissue inhibitor of matrix metalloproteinase, carbon tetrachloride,thioacetamide, superoxide dismutase to scavenge tissue-damaging freeradicals, tumor necrosis factor for cancer therapy, colony stimulatingfactor, interferon, interleukin-2 or other lymphokines to enhance theimmune system, platelet rich plasma, thrombin, peptides such as selfassembly peptide systems, amino acids such as radA based amino acids,hydrogels such as super absorbing hydrogel materials, combinationsthereof, and so forth.

A wide variety of anti-angiogenic factors may be readily utilized withinthe context of the present disclosure. Representative examples includeAnti-Invasive Factor; retinoic acid and derivatives thereof; paclitaxela highly derivatized diterpenoid; Suramin; Tissue Inhibitor ofMetalloproteinase-1; Tissue Inhibitor of Metalloproteinase-2;Plasminogen Activator Inhibitor-1; Plasminogen Activator Inhibitor-2;various forms of the lighter “d group” transition metals such as, forexample, vanadium, molybdenum, tungsten, titanium, niobium, and tantalumspecies and complexes thereof; Platelet Factor 4; Protamine Sulphate(Clupeine); Sulphated Chitin Derivatives (prepared from queen crabshells); Sulphated Polysaccharide Peptidoglycan Complex (SP-PG) (thefunction of this compound may be enhanced by the presence of steroidssuch as estrogen, and tamoxifen citrate); Staurosporine; Modulators ofMatrix Metabolism, including for example, proline analogs(L-azetidine-2-carboxylic acid (LACA), cishydroxyproline,d,L-3,4-dehydroproline, Thiaproline, α,α-dipyridyl, andβ-aminopropionitrile fumarate); MDL 27032(4-propyl-5-(4-pyridinyl)-2(3H)-oxazolone; Methotrexate; Mitoxantrone;Heparin; Interferons; 2 Macroglobulin-serum; ChIMP-3; Chymostatin;β-Cyclodextrin Tetradecasulfate; Eponemycin; Camptothecin; FumagillinGold Sodium Thiomalate (“GST”); D-Penicillamine (“CDPT”);β-1-anticollagenase-serum; α2-antiplasmin; Bisantrene; Lobenzaritdisodium (N-(2)-carboxyphenyl-4-chloroanthronilic acid disodium or“CCA”; Thalidomide; Angostatic steroid; AGM-1470;carboxynaminolmidazole; metalloproteinase inhibitors such as BB94;analogues and derivatives thereof, and combinations thereof.

A wide variety of polymeric drugs may be readily utilized within thecontext of the present disclosure. Representative examples includesteroidal anti-inflammatory agents, non-steroidal anti-inflammatoryagents, and combinations thereof. Examples of the non-steroidalanti-inflammatory agent which may be used with the present disclosureare aspirin, indomethacin, ibuprofen, phenylbutazone, diflusinal, andcombinations thereof.

Examples of the steroidal anti-inflammatory agent which may be used areglucocorticoids such as cortisone and hydrocortisone, betamethasone,dexamethasone, fluprednisolone, prednisone, methylprednisolone,prednisolone, triamcinolone, paramethasone, and combinations thereof.

Although the above bioactive agents have been provided for the purposesof illustration, it should be understood that the present disclosure isnot so limited. In particular, although certain bioactive agents arespecifically referred to above, the present disclosure should beunderstood to include analogues, derivatives and conjugates of suchagents. Moreover, while the above disclosure refers to the placement ofbioactive agents in coatings, such bioactive agents may be combined withany material utilized to form any portion of a medical device, utilizingmeans within the purview of those skilled in the art. Thus, for example,a bioactive agent may be part of a polymeric material, or combined witha polymeric material, utilized to form any portion of a barbed device ofthe present disclosure.

Medical devices in accordance with this disclosure can also include, forexample, biologically acceptable plasticizers, antioxidants andcolorants, which can be impregnated into the filament(s) utilized toform a suture of the present disclosure or included in a coating on amedical device of the present disclosure.

Bioactive agents may be applied onto a barbed medical device of thepresent disclosure utilizing any method within the purview of oneskilled in the art including, for example, dipping, spraying, vapordeposition, brushing, mixing, compounding and the like. In embodiments,a bioactive agent may be deposited within the barb angles, that is, theangle formed between the barb and the medical device surface inaccordance with the present disclosure as described in U.S. patentapplication Ser. No. 11/899,852 filed on Sep. 6, 2007 entitled“Bioactive Substance in a Barbed Suture”, the entire contents of whichare incorporated by reference herein. In embodiments, the bioactiveagent may be deposited on any barbed and/or un-barbed portion of themedical device, such as, for example, on at least a portion of the legsof a staple and/or the crown connecting the legs.

Medical devices of the present disclosure may contain additives such asdyes, pigments, and colorants in order to increase the visibility of thedevice in the surgical field. Any suitable agent such as those agentswithin the purview of those skilled in the art can be used in accordancewith the present disclosure.

The filaments and sutures of the present disclosure may additionallyinclude a needle at one end. In order to facilitate needle attachment toa suture of the present disclosure, conventional tipping agents can beapplied to the braid. Two tipped ends of the suture may be desirable forattaching a needle to each end of the suture to provide a so-calleddouble armed suture. The needle attachment can be made by anyconventional method such as crimping, swaging, and the like.

In some cases, a tubular insertion device (not shown) may be utilized tointroduce a barbed medical device in accordance with the presentdisclosure into tissue. Such a tubular insertion device may have atubular body in which the barbed medical device of the presentdisclosure is disposed, as well as a distal end and a proximal end. Inuse, in some embodiments, the pointed end of a barbed suture of thepresent disclosure may be pushed with the distal end of the tubularinsertion device through skin, tissue, and the like at an insertionpoint. The pointed end of the suture and the distal end of the tubularinsertion device are pushed through the tissue until reaching anendpoint. The proximal end of the tubular insertion device is thengripped and pulled to remove the insertion device, leaving the barbedsuture in place.

Barbed medical devices and placement methods suitable for use accordingto the present disclosure are well known in the art. For example, inembodiments, medical devices of the present disclosure may be utilizedto provide lift to tissue, which may be desirable in certain cosmeticapplications. In other embodiments, medical devices of the presentdisclosure may be utilized to close a tissue opening. In someembodiments, a procedure for closing tissue utilizing barbed staplesinclude inserting a staple cartridge of barbed staples into a surgicalstapler and firing the staple through the tissue to be joined. Thesurgical stapler may or may not include an anvil for deforming thestaple. In some other embodiments, a procedure for closing tissueutilizing barbed sutures includes inserting a first end of amonofilament suture, optionally attached to a needle, at an insertionpoint through the body tissue. The first end of the suture may be pushedthrough body tissue until the first end extends out of the body tissueat an exit point. The first end of the monofilament suture may then begripped and pulled to draw the first portion of the suture through thebody tissue so that an outer surface of the elongated body (of the firstportion) of the suture remains in direct contact with the body tissuebetween the point of insertion and exit point of the first end. Asshown, for example in FIG. 10, the outer surface 630 of the elongatedbody 610 is in direct contact with tissue “t”. The outer surface 630 maybe in direct contact with tissue “t” for any length “L” of the elongatedbody and is not limited to the contact length “L” as shown in FIG. 10.The body tissue may then be manually grouped and advanced along at leastone portion of the monofilament suture to provide the desired amount oflift.

The medical devices of the present disclosure may be utilized in anycosmetic, endoscopic or laparoscopic methods. In addition, sutures ofthe present disclosure may be utilized to attach one tissue to anotherincluding, but not limited to, attaching tissue to a ligament. Specificapplications of cosmetic surgeries include, for example, facelifts,browlifts, thigh lifts, and breast lifts.

While the above description contains many specifics, these specificsshould not be construed as limitations on the scope of the disclosure,but merely as exemplifications of embodiments thereof. Those skilled inthe art will envision many other possibilities within the scope andspirit of the disclosure as defined by the claims appended hereto.

What is claimed is:
 1. A method of forming a compound barb on a staplecomprising: providing a staple having a pair of legs, each leg defininga longitudinal axis; and applying vibrational energy to a cuttingelement to form a compound barb on at least a portion of each legincluding: forming a first cut in the leg, the first cut having a firstratio of cut depth to diameter of the leg; and forming a second cut inthe leg, the second cut having a second ratio of cut depth to diameterof the leg.
 2. The method according to claim 1, further comprisingforming a third cut in the leg, the third cut having a third ratio ofcut depth to diameter of the leg.
 3. The method according to claim 1,wherein the first ratio is approximately 1% to about 40%.
 4. The methodaccording to claim 1, wherein the second ratio is approximately 5% toabout 50%.
 5. The method according to claim 2, wherein the third ratiois approximately 15% to about 50%.
 6. The method according to claim 1,wherein the compound barb on at least a portion of each leg defines aninner surface having a complementary shape with an outer surface of theleg, the inner surface including a first portion disposed at a firstorientation relative to a longitudinal axis of the leg and a secondportion disposed at a second orientation relative to the longitudinalaxis.
 7. The method according to claim 6, wherein an inner surface ofthe compound barb further comprises a third portion disposed at a thirdorientation relative to the longitudinal axis.
 8. The method accordingto claim 7, wherein at least one of the first, second, and thirdportions is substantially linear.
 9. The method according to claim 7,wherein at least one of the first, second, and third portions are atfirst, second, and third angles relative to respective longitudinal axesof each leg.
 10. The method according to claim 9, wherein the firstangle is about 0 degrees to about 90 degrees.
 11. The method accordingto claim 10, wherein the first angle is about 30 degrees to about 40degrees.
 12. The method according to claim 11, wherein the first angleis about 31 degrees to about 38 degrees.
 13. The method according toclaim 9, wherein the second angle is about 0 degrees to about 90degrees.
 14. The method according to claim 13, wherein the second angleis from about 1 degree to about 10 degrees.
 15. The method according toclaim 14, wherein the second angle is from about 2 degrees to about 8degrees.
 16. The method according to claim 9, wherein the third angle isabout 0 degrees to about 90 degrees.
 17. The method according to claim7, wherein at least one of the first, second, and third portions issubstantially non-linear.
 18. The method according to claim 17, whereinthe substantially non-linear portion is cut at a radius relative to thelongitudinal axis of the leg.